1. Field of the Invention
The present invention relates to a fuse unit used for power distribution in a vehicle equipped with two batteries.
2. Description of the Related Art
A fuse unit is directly attached to an onboard battery so as to distribute and supply electricity to loads such as in-vehicle electrical components. Such a fuse unit protects in-vehicle electrical components against an overcurrent by blocking current flow paths. When two batteries are mounted on a vehicle, a fuse unit is directly attached to one of the batteries.
FIGS. 1 and 2 are views showing conventional fuse units 100 and 200, respectively, used in a vehicle on which two batteries are mounted (e.g., Japanese Unexamined Patent Application Publication No. 2011-086510).
The fuse units 100 and 200 include unit bodies 110 and 210 each formed into an L-shape bent substantially at a right angle. The unit bodies 110 and 210 include upper surface portions 111 and 211 each placed and fixed onto the upper surface of a first battery (not shown in the figures) and side surface portions 112 and 212 each positioned along a side surface of the first battery so that the fuse units 100 and 200 are each attached to the first battery in a hanging state.
The unit bodies 110 and 210 include first battery connecting portions 113 and 213, second battery connecting portions 114 and 214, and alternator connecting portions 115 and 215, respectively. In the fuse unit 100 shown in FIG. 1, the first battery connecting portion 113 is located at the upper surface portion 111, and the second battery connecting portion 114 and the alternator connecting portion 115 are located at the side surface portion 112. In the fuse unit 200 shown in FIG. 2, the first battery connecting portion 213 and the alternator connecting portion 215 are located at the upper surface portion 211, and the second battery connecting portion 214 is located at the side surface portion 212.
Outer frames of the unit bodies 110 and 210 are made of an insulating resin. The unit bodies 110 and 210 each include a conductive circuit body including a busbar (not shown in the figures) buried therein. Part of the circuit body necessary for electrical connection is exposed to the outside of each of the unit bodies 110 and 210 as appropriate. In the fuse unit 100 shown in FIG. 1, a first battery connecting end 120 of the circuit body is exposed to the outside on the first battery connecting portion 113. The first battery connecting end 120 is provided with an insertion hole 121 into which a connection bolt of a battery terminal connected to a battery post protruding from the upper surface of the first battery is inserted. The fuse unit 100 is thus connected to the first battery while being fixed onto the upper surface of the first battery. In the fuse unit 200 shown in FIG. 2, a first battery connecting end 220 and an alternator connecting end 240 of the circuit body are exposed to the outside on the first battery connecting portion 213. As in the case of the fuse unit 100 shown in FIG. 1, the first battery connecting end 220 is provided with an insertion hole 221 into which the connecting bolt (not shown in the figure) of the battery terminal connected to the battery post protruding from the upper surface of the first battery is inserted.
The alternator connecting portion 115 of the fuse unit 100 shown in FIG. 1 is provided with an alternator connecting end 140 having an alternator connecting bolt 141. The alternator connecting end 140 is connected to an onboard alternator (not shown in the figure) via a wire. The alternator connecting portion 215 of the fuse unit 200 shown in FIG. 2 is provided with an alternator connecting end 240 having a bolt insertion hole 241. The alternator connecting end 240 is connected to the onboard alternator via a bolt and a wire. The alternator connecting ends 140 and 240 are each connected to the alternator so that the first battery and the second battery are charged with electricity generated by the alternator through driving of the vehicle.
The second battery connecting portions 114 and 214 are each connected to the onboard second battery (not shown in the figures). The fuse unit 100 is provided with a second battery-side connector 131 at a second battery connecting end 130. The second battery-side connector 131 is connected to the second battery via a connector to be mated. The fuse unit 200 is provided with a second battery connecting bolt 231 at a second battery connecting end 230. The second battery connecting bolt 231 is connected to the second battery via a wire.
The fuse units 100 and 200 include load connecting portions 150 and 250 to be connected with loads including in-vehicle electrical components. The load connecting portion 150 of the fuse unit 100 includes load-side connectors 151. The load connecting portion 250 of the fuse unit 200 includes load connecting terminals 251.
The respective fuse units 100 and 200 having the above-described structures include fusible portions (fuses) which are provided for the first battery and the second battery and blow out once an overcurrent flows therethrough so as to prevent the overcurrent from flowing into the first battery and the second battery.
FIG. 3 is a circuit diagram showing the circuit body of the fuse unit 100 provided with the fusible portions. The circuit body of the fuse unit 200 can be illustrated by a similar circuit diagram. As shown in FIG. 3, a first fusible portion 160 is placed between the first battery connecting end 120 (the first battery) and the alternator connecting end 140 (the alternator), and a second fusible portion 170 is placed between the second battery connecting end 130 (the second battery) and the alternator connecting end 140 (the alternator). The alternator connecting end 140 is connected with the load connecting portion 150. Third fusible portions 180 are placed between the load connecting portion 150 and the respective in-vehicle loads 190.
In FIG. 1 and FIG. 2, the corresponding portions in which the first fusible portion and the second fusible portion are located are indicated with the reference numerals 160 and 170, respectively. The first fusible portion 160 and the second fusible portion 170 of the fuse unit 100 are located at the side surface portion 112 of the unit body 110. The first fusible portion 160 of the fuse unit 200 is located at the upper surface portion 211 of the unit body 210, and the second fusible portion 170 is located at the side surface portion 212 of the unit body 210. Such an arrangement is determined depending on the space for each of the fuse units 100 and 200 installed in the vehicle and the configuration of the circuit body (the busbar).
The connection of either the fuse unit 100 or the fuse unit 200 to the first battery, the second battery and the alternator is carried out in the process of assembling the vehicle. With regard to the fuse unit 100, the connecting bolt of the battery terminal connected to the battery post of the first battery is inserted into the first battery connecting end 120 located at the upper surface portion 111. Subsequently, the second battery-side connector 131 located at the side surface portion 112 is fitted to the connector to be mated extending from the second battery so as to be connected to the second battery, and the wire extending from the alternator is fastened to the alternator connecting bolt 141 so that the alternator connecting bolt 141 is connected to the alternator. With regard to the fuse unit 200, the connecting bolt of the battery terminal connected to the battery post of the first battery is inserted into the first battery connecting end 220 located at the upper surface portion 211 so that the first battery connecting end 220 is connected to the first battery, and the bolt connected to the wire extending from the alternator is inserted into the bolt insertion hole 241 of the alternator connecting end 240 so that the alternator connecting end 240 is connected to the alternator. Subsequently, the wire from the second battery is fastened to the second battery connecting bolt 231 located at the side surface portion 212 so that the second battery connecting bolt 231 is connected to the second battery.
The connecting operation described above requires the process of connection of the unit bodies 110 and 210 at the upper surface portions 111 and 212 and also at the side surface portions 112 and 212, which increases the number of steps and complicates the connecting operation. In addition, it is hard to carry out such a connecting operation because it requires the implementation in a small working space.